A number of advanced cancers such as renal cell carcinoma, and sqaumous cell carcinoma of the lung, have proven particularly refractory to chemotherapy. It is therefore warranted to test new agents or new experimental modalities in these tumors. Animal studies suggest that the chemotherapeutic activity of certain alkylating agents can be augmented by the use of oral dimethylsulfoxide (DMSO). Patients with metastatic renal cell carcinoma or squamous cell carcinoma of the lung were therefore treated with DMSO and alkylating agents. Fifteen patients with renal cell carcinoma were treated with DMSO in water and thiotepa. There were no objective responses and DMSO and thiotepa were not useful in this disease. Two patients with squamous cell lung cancer have been started on DMSO in water plus cyclophosphamide. No response or survival data are available in this tumor.